Figure 3. St Firmware Architecture - ST STM32 User Manual

UM2063
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Device Policy Manager (DPM)
DPM's role is to manage all the ports present in the application and to share the power
between them according to the capability of the connected port partners. Once the
negotiation of power has ended, an explicit contract is concluded between them.
DPM can manage VDM exchanges, to manage the alternate modes, only once an
explicit contract is established. This layer is the high level of the USB C power stack
and the place where the user defines the power strategy of its application.
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Policy Engine (PE) layer
The Policy Engine (PE) role is to drive the message sequences according to the sent
message and to its expected response. It allows negotiating power, establishing an
Explicit Contract for the power exchange.
The acceptance or the refusal of a request depends on the response of the DPM
towards a specific power profile.
The PE also handles the Vendor Defined Messages flow, allowing to discover, enter or

Figure 3. ST firmware architecture

UM2063 Rev 5
USB-C™ PD architecture
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